I think the sign "Stop hurting yourself" means to stop hurting ourselves. It says to not do things or actions that will affect not only us but the people that surround us. I think Mr.Phsu put it up there because many kids now have problems that are not known and he wants to remind us to not hurt ourselves.
Well yesterday my classmate drank and had severe consequences. First she only threw up but it got worse after because she was unconscious. Well she hurt herself because she put her life in danger and had to go to the hospital. Others were affected because we didnt relly know what to do and were right there when it all happened.